IFRS 13 permits' options' for fair value measurements. Thus 'an entity uses options in valuation techniques and fair value-hierarchy appropriate to the circumstances and for which sufficient data are available to measure fair value, maximizing the use of relevant observable inputs and minimizing the unobservable inputs. Required: Critically evaluate the 'reliability' of the fair value hierarchy, expressing your views on the three broad levels and the 'observable inputs and unobservable inputs. Also, elaborate on the importance of Fair value measurement techniques and their usefulness to managers.